Steerable catheter

ABSTRACT

A catheter includes a pull wire which extends through two different lumen and attaches to the distal end of the catheter at an off-axis location. By tensioning the pull wire, the catheter can assume various complex curves, depending on the respective lumen through which the pull wire passes.

FIELD OF THE INVENTION

The present invention generally relates to the field of steerablecatheters. More specifically, the invention is directed to a steerablecatheter which includes a single pull wire arranged to allow thecatheter to achieve various complex curvatures.

BACKGROUND OF THE INVENTION

Catheters are used for an ever-growing number of procedures. Forexample, catheters are used for diagnostic, therapeutic, and ablativeprocedures, to name just a few examples. Typically, the catheter ismanipulated through the patient's vasculature and to the intended site,for example, a site within the patient's heart. The catheter typicallycarries one or more electrodes, which may be used for ablation,diagnosis, or the like.

In order to manipulate the catheter through a patient's vasculature, thecatheter must be flexible. In addition, such catheters are preferablysteerable, so that the clinician may impart a desired curve to thecatheter from a remote location in order to pass through curved areaswithin a patient. A conventional steerable catheter includes a pull wirewhich extends through the catheter shaft, and connects to the catheteradjacent the distal end of the catheter at an off-axis location. Thepull wire connects to a control knob, slide actuator, or other suitablemanipulating member that is mounted in a control handle. A form of sucha catheter is disclosed in U.S. Pat. No. 5,383,852 to Stevens-Wright andassigned to the assignee of the rights in the present invention.

While such catheters have gain widespread acceptance in the industry,they nevertheless suffer from certain shortcomings. One shortcoming isthat to achieve relatively complex curves, those catheters requiremultiple pull wires which extend through different lumen and whichconnect to the catheter at different anchoring points. In addition, thepull wires each require a separate manipulating member to tension therespective pull wires. Thus, in a conventional steerable catheter, arelatively large amount of space is occupied by the steering subsystem,which limits the amount of space available for other components.

In addition, ablation catheters typically must assume various curves sothat the ablation electrodes carried on the catheter will come intocontact with a patient's tissue at selected locations. Thus, for thatadditional reason, catheters should be able to assume complex curves.

Accordingly, it will be apparent that there continues to be a need for asteerable catheter which can achieve relatively complex curves tofacilitate manipulation of the catheter through a patient's vasculatureand to an intended site. Moreover, the needs exists for such a catheterwith a steering subsystem that occupies a relatively small amount ofspace within the catheter. The instant invention addresses these needs.

SUMMARY OF THE INVENTION

Briefly, the present invention is in the form of a catheter thatincludes a pull wire which extends through two different lumen andattaches to the distal end of the catheter. By tensioning the pull wire,the catheter can assume various complex curves, depending on thedifferent lumen through which the pull wire passes. A proximal segmentof the catheter can assume a curve in a first plane, while a distalsegment of the catheter can assume a curve in a different plane, therebyachieving a three-dimensional curvature with a single pull wire.

Thus, according to one illustrative embodiment, the present invention isdirected to a medical device including an elongated shaft, the shaftbeing formed with a first lumen extending at least partway through theshaft, and a second lumen extending at least partway through the shaft,the first and second lumen being offset by a predetermined angulardistance, the shaft being further formed with a transition regiondefining a passage leading from the first lumen to the second lumen; asingle pull wire extending through the first lumen, the passage in thetransition region, and the second lumen; and means for actuating thepull wire to impart a desired curve to the shaft.

In another illustrative embodiment, the invention is directed to amedical device that includes a handle including a pull wire tensioningmember, the pull wire tensioning member being manipulable relative tothe handle; an elongated shaft connected to the handle, the shaft beingformed with a first lumen extending at least partway through the shaft,and a second lumen extending at least partway through the shaft, thefirst and second lumen being offset by a predetermined angular distance,the shaft being further formed with a transition region defining apassage leading from the first lumen to the second lumen; and a pullwire connected to the tensioning member and extending through the firstlumen, the passage in the transition region, and the second lumen.

DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention discussed in theabove summary of the invention will be more clearly understood from thefollowing detailed description of preferred embodiments, which areillustrative only, when taken together with the accompanying drawings inwhich:

FIG. 1 is a perspective view of a steerable medical device including asteering subsystem according to one illustrative embodiment of thepresent invention;

FIG. 2 is a partial perspective view of the medical device of FIG. 1 andshowing the distal end of the device actuated to assume a first curvedconfiguration according to one illustrative embodiment of the invention;

FIG. 2A is a partial perspective view of the medical device of FIG. 1and showing the distal end of the device actuated to assume a secondcurved configuration according to a second illustrative embodiment ofthe invention;

FIG. 3 is a cross-sectional view taken along the line 3—3 of FIG. 2 andlooking in the direction of the arrows;

FIG. 4 is a fragmented, sectional view of the shaft portion of themedical device shown in FIG. 1;

FIG. 5 is a partial sectional view of the shaft portion of the medicaldevice shown in FIG. 1;

FIG. 6 is a cross-sectional view taken along the line 6—6 of FIG. 5;

FIG. 7 is a cross-sectional view taken along the line 7—7 of FIG. 5;

FIG. 8 is a cross-sectional view of another illustrative embodiment ofthe medical device of FIG. 1;

FIG. 9 is a cross-sectional view taken along the line 9—9 of FIG. 8; and

FIG. 10 is a cross-sectional view taken along the line 10—10 of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and particularly to FIG. 1, there isshown a medical device 10 according to one illustrative embodiment ofthe present invention. In one illustrative embodiment, the medicaldevice 10 includes a steering subsystem, generally designated 12, whichis operative to impart a desired curve to the catheter. In oneillustrative embodiment, the catheter includes one or more electrodes14, one or more of which may be slidably mounted over an elongatedcatheter shaft 16 of the device 10 and which are selectively movablerelative to the catheter shaft in either a distal or proximal directionalong the catheter shaft 16. Thus, for example, in an ablationprocedure, the device 10 may be manipulated through a patient's bloodvessels by means of the steering subsystem 12 until the electrode 14 isdisposed in a desired location within the patient's body. The electrodemay then be used for ablation, for sensing electrical activity withinthe heart, or any other suitable function.

Referring to FIG. 1, the medical device 10 in one illustrativeembodiment is in the form of a catheter, for example, an ablationcatheter, therapeutic catheter, mapping catheter, or other diagnosticcatheter. It will be apparent that the medical device 10 of the presentinvention can take many different forms, such as any medical devicehaving an insertion member to be inserted into a patient's body. In theillustrative embodiment, the catheter includes the catheter shaft 16,which is preferably a flexible shaft which can be manipulated through apatient's blood vessels and to a site of interest within the patient'sbody, as is described in greater detail below. The catheter shaftdefines a plurality of interior lumen 22 (FIGS. 6 and 7) which areformed having predetermined cross-sectional dimensions for passingvarious components through the respective lumen, as is described ingreater detail below.

In one embodiment, the medical device 10 includes a control handle 24for manipulating the steering subsystem 12 (FIG. 1). The catheter handlemay take many different forms. One suitable form of control handle isshown in FIG. 1 and is disclosed in greater detail in U.S. Pat. No.5,462,527 to Stevens-Wright, the disclosure of which is hereby expresslyincorporated by reference as if fully set forth herein. Briefly, thecontrol handle includes a control knob 26 which is rotatable relative tothe handle. The control knob is preferably connected to a component ofthe steering subsystem 12, as is described in greater detail below.Another suitable form of control handle is disclosed in U.S. Pat. No.5,611,777 to Bowden et al., which is expressly incorporated herein byreference.

The control handle 24 is preferably connected to a connector 23, whichconnects to a suitable power supply (not shown) to provide ablationenergy to the slidable electrode 14, and to diagnostic equipment (notshown) to transmit sensing signals generated by the catheter electrodes,as is well known in the art and described in greater detail below.

According to one illustrative embodiment of the invention, the controlknob 26 is engaged to one end of a pull wire 29 which extends through atleast two lumens 22 and 22′ in the catheter shaft 16 and is connected tothe distal end portion of the catheter at an off-axis location. As such,tension applied to the pull wire causes the catheter shaft to curve in apredetermined direction or directions, as is shown in FIGS. 2, 2A, and3, and is described in greater detail below.

Referring to FIGS. 2A and 5 through 7, there is shown one illustrativeembodiment of the medical device 10 of the invention. The single pullwire 29 extends from the control knob 26 through a first lumen 22 to atransition region 25 within the shaft 16. In the transition region, thepull wire transitions to a second lumen 22′ which is angularly spaced180° from the first lumen. The pull wire then extends through the secondlumen toward the distal end of the catheter, and connects to thecatheter at an off-axis location.

Thus, when tension is applied to the pull wire 29, the proximal regionwill curve in a first direction and the distal region will curve in theopposite direction (i.e., the two curves lie in the same plane but facein directions 180° apart) (FIG. 2A).

Preferably, the proximal and distal portions of the catheter shaft 16separated by the transition region 25 are formed of differentcompositions having different durometers, which allows for differentcurves for the respective regions from the single pull wire 29. Thus,when tension is created in the pull wire 29, the portion formed ofsofter material will curve to a greater extent than the more rigidportion. As such, by selecting the durometers of the proximal and distalportions, the extent to which the respective portions curve can bedetermined. In addition, the catheter shaft may be formed of arelatively rigid material up to the proximal portion, such that when thepullwire is tensioned, only the proximal and distal portions of thecatheter shaft curve, and the majority of the shaft remains generallylinear (FIG. 2A).

Referring now to FIGS. 2, 3, and 8 through 10, there is shown a secondillustrative embodiment of the medical device 10 of the invention. Inthis embodiment, the pull wire 29 extends through a first lumen 22, andthen transitions to a second lumen 22′ that is angularly spaced 90° fromthe first lumen. The pull wire then extends through the second lumen andconnects to the distal end of the catheter at an off-axis location.

Thus, when tension is applied to the pull wire 29, the proximal segmentcurves in a first plane, and the distal segment curves in a plane thatis orthogonal to the first plane (i.e., shifted 90° from the firstplane) (FIGS. 2 and 3). As such, the catheter assumes athree-dimensional configuration with the single pull wire 29.

It will be apparent to those skilled in the art that the pull wire 29may be extended through lumen that are angularly spaced at some angleother than 90° or 180°. When the pull wire has a 180° transition betweenthe lumen, the corresponding curves are coplanar. However, when the pullwire transition is less than 180°, the corresponding curves are notcoplanar, resulting in a three-dimensional configuration for thecatheter.

Thus, depending on the desired configuration, the pull wire transitioncan be any angle, such as 30°, 45°, 60°, or any other angle.

In addition, while in the illustrative embodiments, the pull wire 29extends through two different lumen 22 and 22′, it will be understood bythose skilled in the art that the pull wire may extend through three ormore lumen, with the catheter shaft including two or more transitionregions between the respective lumen. In that manner, the catheter willhave three or more different curved regions, which may be coplanar ornot, depending on the transition angles between the respective lumen, asdescribed above.

The catheter shaft 16 preferably includes the one or more electrodes 14disposed at strategically placed locations relative to the respectivecurved regions, such that when the pull wire is tensioned, theelectrodes are deployed into operative positions for contacting apatient's tissue. One or more of the electrodes 14 may be displaceablerelative to the catheter shaft by a relatively stiff displacing memberin the form of a mandrel (not shown) which includes a first, proximalend securely connected to a second control knob (not shown) or othersuitable member formed on the handle 24. The mandrel may be in the formof a shaft, stiff wire, hypotube, or the like, and extends distally fromthe control knob through the handle 24, through one of the lumens 22,and then extends laterally with respect to the catheter shaft and intoengagement with the inside surface of the slidable electrode.

Such a construction is disclosed in detail in U.S. patent applicationSer. No. 09/203,922, and now U.S. Pat. No. 6,178,354, the disclosure ofwhich is expressly incorporated herein by reference.

In operation, a clinician inserts the distal end of the catheter shaft16 into a patient's blood vessels and manipulates the shaft through thevasculature to an intended site. As the catheter is manipulated throughthe vasculature, the clinician may periodically tension the pull wire 29to impart the predetermined curvature to the catheter so that it maypass through curved regions within the patient's body (FIGS. 2, 2A, and3). In addition, once the catheter is disposed at the intended sitewithin the patient, the pull wire 29 may be tensioned so that thecatheter shaft 16 assumes the desired curvature, with one or more of theelectrodes 14 carried along the catheter shaft being deployed intocontact with a patient's tissue for diagnostic, therapeutic, and/orablative procedures. Once the procedure or procedures are completed, theclinician then removes the catheter from the patient.

Thus, for example, the distal end region of the catheter may be designedso that it assumes a predetermined curve for manipulation purposesthrough the patient's vasculature, while one or more other cathetershaft regions may be designed so that they assume various curves forelectrode deployment purposes and the like.

From the foregoing, it will be apparent to those skilled in the art thatthe present invention provides a medical device which includes asteering subsystem that facilitates manipulation of the medical devicethrough a patient's vasculature, and which also facilitates deploymentof one or more electrodes into contact with a patient's tissue. Inaddition, the medical device of the present invention includes asteering subsystem which uses a relatively small number of components.

Having thus described preferred embodiments of the present invention, itis to be understood that the above described arrangement and system ismerely illustrative of the principles of the present invention, and thatother arrangements and systems may be by those skilled in the artwithout departing from the spirit and scope of the invention as claimedbelow.

What is claimed is:
 1. A catheter comprising: an elongated shaft, theshaft having a length and an axis and being formed with a first lumenextending at least partway along an axis parallel to the axis of theshaft, and a second lumen extending at least partway along an axisparallel to the axis of the shaft, the first lumen and second lumenoccupying separate regions along the length of the shaft and beingoffset by a predetermined angular distance, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; a pull wire extending through the firstlumen, the passage in the transition region, and the second lumen; andmeans for actuating the pull wire in one direction to both bend one ofthe regions in a first direction and another of the regions in a seconddirection that is different from the first direction.
 2. A cathetercomprising: an elongated shaft, the shaft being formed with a firstlumen extending at least partway through the shaft, and a second lumenextending at least partway through the shaft, the first and second lumenbeing offset by a predetermined angular distance, the shaft beingfurther formed with a transition region defining a passage leading fromthe first lumen to the second lumen; a pull wire extending through thefirst lumen, the passage in the transition region and the second lumen;and means for actuating the pull wire to impart a desired curve to theshaft, wherein the first and second lumen are offset by an angle of 90degrees.
 3. The catheter of claim 1, wherein the first and second lumenare offset by an angle of 180 degrees.
 4. A catheter comprising: anelongated shaft, the shaft being formed with a first lumen extending atleast partway through the shaft, and a second lumen extending at leastpartway through the shaft, the first and second lumen being offset by apredetermined angular distance, the shaft being further formed with atransition region defining a passage leading from the first lumen to thesecond lumen; a pull wire extending through the first lumen, the passagein the transition region and the second lumen; and means for actuatingthe pull wire to impart a desired curve to the shaft, wherein the firstand second lumen are offset by an angle of less than 180 degrees.
 5. Thecatheter of claim 1, wherein the first and second lumen extend along thelength of the shaft.
 6. The catheter of claim 1, wherein the means foractuating comprises a handle and a pull wire tensioning member mountedto the handle, wherein the tensioning member is manipulable relative tothe handle, and wherein the pull wire is connected to the tensioningmember, such that manipulation of the tensioning member tensions thepull wire and causes the shaft to assume a predetermined curve.
 7. Amedical device comprising: a handle including a pull wire tensioningmember, the pull wire tensioning member being manipulable relative tothe handle; an elongated shaft connected to the handle, the shaft havinga length and an axis and being formed with a first lumen extending atleast partway along an axis parallel to the axis of the shaft, and asecond lumen extending at least partway along an axis parallel to theaxis of the shaft, the first lumen and second lumen occupying separateregions along the length of the shaft and being offset by apredetermined angular distance, the shaft being further formed with atransition region defining a passage leading from the first lumen to thesecond lumen; and a pull wire connected to the tensioning member andextending through the first lumen, the passage in the transition region,and the second lumen; whereby tensioning the pull wire in one directionboth bends one of the regions in a first direction and another of theregions in a second direction that is different from the firstdirection.
 8. A medical device comprising: a handle including a pullwire tensioning member, the pull wire tensioning member beingmanipulable relative to the handle; an elongated shaft connected to thehandle, the shaft being formed with a first lumen extending at leastpartway through the shaft, and a second lumen extending at least partwaythrough the shall, the first and second lumen being offset by apredetermined angular distance, the shaft being further formed with atransition region defining a passage leading from the first lumen to thesecond lumen; and a pull wire connected to the tensioning member andextending through the first lumen, the passage in the transition region,and the second lumen, wherein the first and second lumen are offset byan angle of 90 degrees.
 9. The catheter of claim 7, wherein the firstand second lumen are offset by an angle of 180 degrees.
 10. A medicaldevice comprising: a handle including a pull wire tensioning member, thepull wire tensioning member being manipulable relative to the handle; anelongated shaft connected to the handle, the shaft being formed with afirst lumen extending at least partway through the shaft, and a secondlumen extending at least partway through the shaft, the first and secondlumen being offset by a predetermined angular distance, the shaft beingfurther formed with a transition region defining a passage leading fromthe first lumen to the second lumen; and a pull wire connected to thetensioning member and extending through the first lumen, the passage inthe transition region, and the second lumen, wherein the first andsecond lumen are offset by an angle of less than 180 degrees.
 11. Thecatheter of claims 7, wherein the first and second lumen extend alongthe length of the shaft.
 12. A medical device comprising: an elongatedshaft, the shaft having a length and an axis and being formed with afirst lumen extending at least partway along an axis parallel to theaxis of the shaft, and a second lumen extending at least partway alongan axis parallel to the axis of the shaft, the first lumen and secondlumen occupying separate regions along the length of the shaft and beingoffset by a predetermined angular distance, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; a pull wire extending through the firstlumen, the passage in the transition region, and the second lumen; and apull wire tensioning member for actuating the pull wire in one directionto both bend one of the regions in a first direction and another of theregions in a second direction that is different from the firstdirection.
 13. A medical device comprising: an elongated shaft, theshaft being formed with a first lumen extending at least partway throughthe shaft, and a second lumen extending at least partway through theshaft, the first and second lumen being offset by a predeterminedangular distance, the shaft being further formed with a transitionregion defining a passage leading from the first lumen to the secondlumen; a pull wire extending through the first lumen, the passage in thetransition region, and the second lumen; and a pull wire tensioningmember for actuating the pull wire to impart a desired curve to theshaft, wherein the first and second lumen are offset by an angle of 90degrees.
 14. The catheter of claim 12, wherein the first and secondlumen are offset by an angle of 180 degrees.
 15. A medical devicecomprising: an elongated shaft, the shaft being formed with a firstlumen extending at least partway through the shaft, and a second lumenextending at least partway through the shaft, the first and second lumenbeing offset by a predetermined angular distance, the shaft beingfurther formed with a transition region defining a passage leading fromthe first lumen to the second lumen; a pull wire extending through thefirst lumen, the passage in the transition region, and the second lumen;and a pull wire tensioning member for actuating the pull wire to imparta desired curve to the shaft, wherein the first and second lumen areoffset by an angle of less than 180 degrees.
 16. The catheter of claim12, wherein the first and second lumen extend along the length of theshaft.
 17. A catheter comprising: an elongated shaft, the shaft having alength and an axis and being formed with a first lumen extending atleast partway along an axis parallel to the axis of the shaft, and asecond lumen extending at least partway along an axis parallel to theaxis of the shaft, the first lumen and second lumen occupying separateregions along the length of the shaft and being offset by apredetermined angular distance, the shaft being further formed with atransition region defining a passage leading from the first lumen to thesecond lumen: a pull wire extending through the first lumen the passagein the transition region, and the second lumen; and means for actuatingthe pull wire in one direction to bend one of the regions in a firstdirection and another of the regions in a second direction that isdifferent from the first direction, wherein the first and second lumenare offset by an angle of 90 degrees.
 18. A catheter comprising: anelongated shaft, the shaft having a length and an axis and being formedwith a first lumen extending at least partway along an axis parallel tothe axis of the shaft, and a second lumen extending at least partwayalong an axis parallel to the axis of the shaft, the first lumen andsecond lumen occupying separate regions along the length of the shaftand being offset by a predetermined angular distance, the shaft beingfurther formed with a transition region defining a passage leading fromthe first lumen to the second lumen; a pull wire extending through thefirst lumen, the passage in the transition region, and the second lumen;and means for actuating the pull wire in one direction to bend one ofthe regions in a first direction and another of the regions in a seconddirection that is different from the first direction, wherein the firstand second lumen are offset by an angle of less than 180 degrees. 19.The catheter of claim 1, wherein a portion of the catheter adjacent thefirst lumen is formed of a composition having a first durometer, and aportion of the catheter adjacent the second lumen is formed of acomposition having a second durometer different from the firstdurometer.
 20. A medical device comprising: a handle including a pullwire tensioning member, the pull wire tensioning member beingmanipulable relative to the handle; an elongated shaft connected to thehandle, the shaft having a length and an axis and being formed with afirst lumen extending at least partway along an axis parallel to theaxis of the shaft, and a second lumen extending at least partway alongan axis parallel to the axis of the shaft, the first lumen and secondlumen occupying separate regions along the length of the shaft and beingoffset by a predetermined angular distance, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; and a pull wire connected to thetensioning member and extending through the first lumen, the passage inthe transition region, and the second lumen; whereby tensioning the pullwire in one direction bends one of the regions in a first direction andanother of the regions in a second direction that is different from thefirst direction, wherein the first and second lumen are offset by anangle of 90 degrees.
 21. A medical device comprising: a handle includinga pull wire tensioning member, the pull wire tensioning member beingmanipulable relative to the handle; an elongated shaft connected to thehandle, the shaft having a length and an axis and being formed with afirst lumen extending at least partway alone an axis parallel to theaxis of the shaft, and a second lumen extending at least partway alongan axis parallel to the axis of the shaft, the first lumen and secondlumen occupying separate regions along the length of the shaft and beingoffset by a predetermined angular distance, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; and a pull wire connected to thetensioning member and extending through the first lumen, the passage inthe transition region, and the second lumen; whereby tensioning the pullwire in one direction bends one of the regions in a first direction andanother of the regions in a second direction that is different from thefirst direction, wherein the first and second lumen are offset by anangle of less than 180 degrees.
 22. The medical device of claim 7,wherein a portion of the catheter adjacent the first lumen is formed ofa composition having a first durometer, and a portion of the catheteradjacent the second lumen is formed of a composition having a seconddurometer different from the first durometer.
 23. A medical devicecomprising: an elongated shaft, the shaft having a length and an axisand being formed with a first lumen extending at least partway along anaxis parallel to the axis of the shaft, and a second lumen extending atleast partway along an axis parallel to the axis of the shaft, the firstlumen and second lumen occupying separate regions along the length ofthe shaft and being offset by a predetermined angular distance, theshaft being further formed with a transition region defining a passageleading from the first lumen to the second lumen; a pull wire extendingthrough the first lumen, the passage in the transition region, and thesecond lumen; and a pull wire tensioning member for actuating the pullwire in one direction to bend one of the regions in a first directionand another of the regions in a second direction that is different fromthe first direction, wherein the first and second lumen are offset by anangle of 90 degrees.
 24. A medical device comprising: an elongatedshaft, the shaft having a length and an axis and being formed with afirst lumen extending at least partway along an axis parallel to theaxis of the shaft, and a second lumen extending at least partway alongan axis parallel to the axis of the shaft, the first lumen and secondlumen occupying separate regions along the length of the shaft and beingoffset by a predetermined angular distance, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; a pull wire extending through the firstlumen, the passage in the transition region, and the second lumen; and apull wire tensioning member for actuating the pull wire in one directionto bend one of the regions in a first direction and another of theregions in a second direction that is different from the firstdirection, wherein the first and second lumen are offset by an angle ofless than 180 degrees.
 25. The medical device of claim 12, wherein aportion of the catheter adjacent the first lumen is formed of acomposition having a first durometer, and a portion of the catheteradjacent the second lumen is formed of a composition having a seconddurometer different from the first durometer.
 26. A medical devicecomprising: an elongated shaft having a proximal end, a distal end andan axis, the shaft being formed with a first lumen extending at leastpartway generally along an axis parallel to the axis of the shaft and asecond lumen extending at least partway generally along an axis parallelto the axis of the shaft, the first lumen and second lumen being offsetby a predetermined angular distance, the shaft being further formed witha transition region defining a passage leading from a distal end of thefirst lumen to a proximal end the second lumen; a pull wire extendingthrough the first lumen, the passage in the transition region, and thesecond lumen; and a pull wire tensioner for actuating the pull wire toimpart a desired curve to the shaft.
 27. A medical device comprising: anelongated shaft having a proximal end and a distal end, the shaft beingformed with a first lumen extending at least partway through the shaftand a second lumen extending at least partway through the shaft, thefirst and second lumen being offset by a predetermined angular distance,the shaft being further formed with a transition region defining apassage leading from a distal end of the first lumen to a proximal endof the second lumen; a pull wire extending through the first lumen, thepassage in the transition region, and the second lumen; and a pull wiretensioner for actuating the pull wire to impart a desired curve to theshaft; wherein the first and second lumen are offset by an angle of lessthan 180 degrees.
 28. A medical device comprising: an elongated shafthaving a proximal end, a distal end and an axis, the shaft being formedwith a first lumen extending at least partway generally along an axisparallel to the axis of the shaft and a second lumen extending at leastpartway generally along an axis parallel to the axis of the shaft, thefirst lumen and second lumen being offset by a predetermined angulardistance and at least a portion of the second lumen being locateddistally to the entirety of the first lumen, the shaft being furtherformed with a transition region defining a passage leading from thefirst lumen to the second lumen; a pull wire extending through the firstlumen, the passage in the transition region, and the second lumen; and apull wire tensioner for actuating the pull wire to impart a desiredcurve to the shaft.
 29. The medical device of claim 28, wherein theentirety of the second lumen is located distally to the entirety of thefirst lumen.
 30. A medical device comprising: an elongated shaft havinga proximal end and a distal end, the shaft being formed with a firstlumen extending at least partway through the shaft and a second lumenextending at least partway through the shaft, the first and second lumenbeing offset by a predetermined angular distance and at least a portionof the second lumen being located distally to the entirety of the firstlumen, the shaft being further formed with a transition region defininga passage leading from the first lumen to the second lumen; a pull wireextending through the first lumen, the passage in the transition region,and the second lumen; and a pull wire tensioner for actuating the pullwire to impart a desired curve to the shaft; wherein the first andsecond lumen are offset by an angle of less than 180 degrees.
 31. Themedical device of claim 28, wherein the entirety of the second lumen islocated distally to the entirety of the first lumen.
 32. The medicaldevice of claim 26, wherein the first and second lumen are offset by anangle of 180 degrees.
 33. The medical device of claim 26, wherein thefirst and second lumen are offset by an angle of less than 180 degrees.34. The medical device of claim 26, wherein the first and second lumenare offset by an angle of 90 degrees.
 35. The medical device of claim26, wherein a portion of the shaft adjacent the first lumen is formed ofa composition having a first durometer, and a portion of the shaftadjacent the second lumen is formed of a composition having a seconddurometer different from the first durometer.
 36. The medical device ofclaim 27, wherein the first and second lumen are offset by an angle of90 degrees.
 37. The medical device of claim 27, wherein a portion of theshaft adjacent the first lumen is formed of a composition having a firstdurometer, and a portion of the shaft adjacent the second lumen isformed of a composition having a second durometer different from thefirst durometer.
 38. The medical device of claim 28, wherein the firstand second lumen are offset by an angle of 180 degrees.
 39. The medicaldevice of claim 28, wherein the first and second lumen are offset by anangle of less than 180 degrees.
 40. The medical device of claim 28,wherein the first and second lumen are offset by an angle of 90 degrees.41. The medical device of claim 28, wherein a portion of the shaftadjacent the first lumen is formed of a composition having a firstdurometer, and a portion of the shaft adjacent the second lumen isformed of a composition having a second durometer different from thefirst durometer.
 42. The medical device of claim 30, wherein the firstand second lumen are offset by an angle of 90 degrees.
 43. The medicaldevice of claim 30, wherein a portion of the shaft adjacent the firstlumen is formed of a composition having a first durometer, and a portionof the shaft adjacent the second lumen is formed of a composition havinga second durometer different from the first durometer.
 44. The catheterof claim 2, wherein a portion of the catheter adjacent the first lumenis formed of a composition having a first durometer, and a portion ofthe catheter adjacent the second lumen is formed of a composition havinga second durometer different from the first durometer.
 45. The catheterof claim 4, wherein a portion of the catheter adjacent the first lumenis formed of a composition having a first durometer, and a portion ofthe catheter adjacent the second lumen is formed of a composition havinga second durometer different from the first durometer.
 46. The medicaldevice of claim 8, wherein a portion of the shaft adjacent the firstlumen is formed of a composition having a first durometer, and a portionof the shaft adjacent the second lumen is formed of a composition havinga second durometer different from the first durometer.
 47. The medicaldevice of claim 10, wherein a portion of the shaft adjacent the firstlumen is formed of a composition having a first durometer, and a portionof the shaft adjacent the second lumen is formed of a composition havinga second durometer different from the first durometer.
 48. The medicaldevice of claim 13, wherein a portion of the shaft adjacent the firstlumen is formed of a composition having a first durometer, and a portionof the shaft adjacent the second lumen is formed of a composition havinga second durometer different from the first durometereter.
 49. Themedical device of claim 15, wherein a portion of the shaft adjacent thefirst lumen is formed of a composition having a first durometer, and aportion of the shaft adjacent the second lumen is formed of acomposition having a second durometer different from the firstdurometer.
 50. The catheter of claim 17, wherein a portion of thecatheter adjacent the first lumen is formed of a composition having afirst durometer, and a portion of the catheter adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.
 51. The catheter of claim 18, wherein a portion of thecatheter adjacent the first lumen is formed of a composition having afirst durometer, and a portion of the catheter adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.
 52. The medical device of claim 20, wherein a portionof the shaft adjacent the first lumen is formed of a composition havinga first durometer, and a portion of the shaft adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.
 53. The medical device of claim 21, wherein a portionof the shaft adjacent the first lumen is formed of a composition havinga first durometer, and a portion of the shaft adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.
 54. The medical device of claim 23, wherein a portionof the shaft adjacent the first lumen is formed of a composition havinga first durometer, and a portion of the shaft adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.
 55. The medical device of claim 24, wherein a portionof the shaft adjacent the first lumen is formed of a composition havinga first durometer, and a portion of the shaft adjacent the second lumenis formed of a composition having a second durometer different from thefirst durometer.